This proposal represents the integrated efforts by a local city mental health authority (Baltimore Mental Health Systems, Inc.), a state-operated community mental health center (the Walter P. Carter Center), an established program serving the general homeless community (Health Care for the Homeless), the Baltimore Alliance for the Mentally Ill, and a university-based research program on severe mental illness to achieve a better understanding of how to serve homeless persons with severe mental illness (HSMI). We will implement a randomized evaluation of an assertive community treatment (ACT) program adapted to serve the homeless mentally ill in comparison to the current system of services to test the following hypotheses: 1) The ACT program will increase the access to general health and mental health services for the HSMI. 2) The ACT program will increase their access to basic social services and necessities, including stable housing, food, and social entitlements (SSI, SSDI, Medicaid, etc.). 3) The ACT program will enhance the mental health, general health, functional status, and quality of life of the HSMI and reduce family burden. 4) Specific relationships will exist between improved access to services and basic necessities on the one hand and client outcomes on the other. For example, better access to mental health services will predict better mental health outcomes; enhanced access to housing will predict better housing outcomes. 5) The service and outcome effects of the ACT identified in Hypotheses 1-3 will differ between those HSMI entered via a hospitalization and those entered via street and shelter outreach. 6) The total costs under the ACT model will be equivalent to those under usual services. Finally, an ethnographic study will develop life histories on a sub-set of the subjects as well as a social geography of the service environment encountered by the HSMI in Baltimore.